Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 698 (HORNS)DESCRIPTION AND OPERATIONHORNS SYSTEM DESCRIPTION AND OPERATIONSYSTEM OPERATION
1999 GMC Forward Control 5.7 R, Automatic
System Operation
1999 GMC Forward Control 5.7 R, AutomaticSECTION System Operation
WARNING: This page is about a different car, the 2003 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.
The vehicle horn system is activated under the following conditions:
- The horn switch is depressed.
- On vehicles equipped with content theft deterrent (UA6), the body control module (BCM) may command the horns on. The BCM commands the horns on under any of the following conditions:
- When the content theft deterrent system detects a vehicle intrusion. For further information refer to CONTENT THEFT DETERRENT (CTD) DESCRIPTION AND OPERATION in Theft Deterrent.
- When the panic button is depressed on the remote control door lock transmitter, For further information refer to KEYLESS ENTRY SYSTEM DESCRIPTION AND OPERATION in Keyless Entry.
- When the keyless entry system is used to lock the vehicle, a horn chirp may sound to notify the driver that the vehicle has been locked. The notification feature may be enabled or disabled through personalization. For further information refer to KEYLESS ENTRY SYSTEM DESCRIPTION AND OPERATION in Keyless Entry.
RENDER: 1.0x
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.